'We promised you the liberation of Fallujah and we retook it': Iraqi PM

Iraq's Prime Minister Haider al-Abadi said his military had recaptured most of Fallujah from the Islamic State (IS) group and that only "small pockets" of resistance remained.

"We promised you the liberation of Fallujah and we retook it," Abadi said in a statement on Friday. "Our security forces control the city except for small pockets that need to be cleared within the coming hours."

His statement came shortly after Iraqi commanders reported their troops had raised the national flag over the main government compound in Fallujah, a breakthrough in the nearly four-week offensive against IS.

This latest setback leaves IS on the brink of losing a significant stronghold of its two-year-old "caliphate," which has also lost territory in neighbouring Syria and in Libya in recent weeks.

Elite federal forces met limited resistance from IS militants, who were redeploying on the western outskirts of Fallujah, the commanders told the AFP news agency.

"The counter-terrorism service and the rapid response forces have retaken the government compound in the centre of Fallujah," said the operation's overall commander, Lieutenant General Abdulwahab al-Saadi.

Saadi said the Iraqi flag was raised above government buildings in the compound and claimed that "Iraqi forces have now liberated 70 percent of the city".

The government lost control of Fallujah in 2014, months before IS took second-city Mosul and swept across large parts of the country.

Fallujah, which lies just 50km west of Baghdad, has been one of IS's most emblematic bastions and its loss leaves Mosul as the only major Iraqi city under its control.

The US-led coalition, which carried out air strikes in support of the Fallujah operation, initially favoured focusing efforts on recapturing Mosul.

Abadi, who was facing huge political pressure over the reform of his government when he declared the launch of the Fallujah operation, vowed to defeat IS nationwide by the end of the year.

Security officials said many IS members had managed to slip out of Fallujah by blending in with fleeing civilians in recent days, in some cases paying off security forces.

"The top leaders are mostly gone and those left behind to defend the city are not their best fighters, which explains their performance," said a security officer, speaking on condition of anonymity.